One of the most promising advantages for health information exchange (HIE) is improved patient safety. Up to 18% of the patient safety errors generally and as many as 70% of adverse drug events could be eliminated if the right information about the right patient is available at the right time. Health information exchange makes this possible. Here we present an overview of six different ways in which HIE can improve patient safety-improved medication information processing, improved laboratory information processing, improved radiology information processing, improved communication among providers, improved communication between patients and providers, and improved public health information processing. Within the area of improved medication information processing we discuss drug-allergy information processing, drug-dose information processing, drug-drug information processing, drug-diagnosis information processing, and drug-gene information processing. We also briefly discuss HIE and decreased patient safety as well as standards and completeness of information for HIE and patient safety.